贮存温度和时间对大熊猫粪便样品皮质醇浓度的影响

Effects of storage temperature and duration on cortisol concentration in feces of giant pandas(Ailuropoda melanoleuca)

通过非损伤性取样比如粪便样品监测野生动物受胁迫的水平已成为一个重要的手段,然而针对从野外采集的样品,其运输和贮存温度条件是否干扰分析结果,尚未有过报道。为评估不同贮存温度和天数对野生动物粪便样品中皮质醇浓度的影响,我们将大熊猫的新鲜粪便置于3种模拟条件(0℃、10℃和22℃),并进行连续6 d的检测分析。结果表明,贮存天数对粪样中皮质醇浓度有显著影响(F5,107=7.501,P=0.001),但温度则无显著影响(F2,107=1.094,P=0.366)。粪样在0℃、10℃和22℃条件下贮存6 d,皮质醇浓度与贮存前的基准值之间均不存在显著差异(0℃:F6,41=1.274,P=0.290;10℃:F6,41=2.027,P=0.084;22℃:F6,41=1.009,P=0.434)。结果提示在室温条件下短期运输和贮存(不超过6 d),不会引起大熊猫粪便样品中皮质醇浓度的显著变化。该结果对于野外所采集的粪便样品运输和贮存具有一定的指导意义。

Noninvasive sampling methods, e.g. collection and analysis of fecal samples, are increasingly used to monitor the stress levels of wild animals, yet the effects of storage temperature and of the duration of transportation and storage of fresh fecal samples on fecal cortisol concentrations remain unclear. We collected one fresh fecal dropping daily from each of two captive giant pandas （Ailuropoda melanoleuca） on three consecutive days at Beijing Zoo. Each dropping was mixed thoroughly and then allocated to a 50 g sample. We took a 5 g sub-sample from each individual fecal sample and froze it at -20℃ ; this was used as the pre-treatment baseline. Next, we divided the remainder of each fecal sample into three 15 g sub-samples which were randomly assigned to be stored at 0℃, 10℃ and 22℃ for six days. The glucocorticoids were extracted from each sub-sample once per day. The fecal cortisol concentrations were finally assayed by using commercial ^125I cortisol radioimmunoassay kits. The results showed that the fecal cortisol concentrations were not significantly affected by storage temperature （F2.107 = 1.094, P = 0. 366）, but were affected by the duration of storage （Fs,107 =7. 501, P = 0. 001 ）. After storage at 0℃, 10℃ and 22℃ for six days, fecal cortisol concentrations were similar to those of the pretreatment baseline fecal samples （ F6,41 = 1. 274, P = 0. 290 ; F6,41 = 2. 027, P = 0. 084 and F6,4 = 1. 009, P = 0. 434）. The results of this study suggest that short-term （ no longer than 6 days） transportation or storage of fecal samples at temperatures below 22℃ does not alter radioimmunoassay results for fecal cortisol concentrations in the giant panda. Our results will aid fecal sample collection for monitoring stress hormones in wild pandas, and thus their conservation as well.